TELNET OUTPUT FORMFEED DISPOSITION OPTIONRFC 655, NIC 31158 (Oct. 25, 1974)
D. Crocker (UCLA-NMC)
Online file: [ISI]<DCROCKER>NAOFFD.TXT
TELNET OUTPUT FORMFEED DISPOSITION OPTION
1. Command name and code
NAOFFD - 13
(Negotiate About Output Formfeed Disposition)
2. Command meanings
In the following, we are discussing a simplex connection, as described in
the NAOL and NAOP Telnet Options specifications.
IAC DO NAOFFD
The data sender requests or agrees to negotiate about output
formfeed disposition with the data receiver. In the case
where agreement has been reached and in the absence of
further subnegotiations, the data receiver is assumed to be
handling output formfeeds.
IAC DON'T NAOFFD
The data sender refuses to negotiate about output formfeed
disposition with the data receiver, or demands a return to
the unnegotiated default mode.
IAC WILL NAOFFD
The data receiver requests or agrees to negotiate about
output formfeed disposition with the sender. In the case
where agreement has been reached and in the absence of
further subnegotiations, the data receiver alone is assumed
to be handling output formfeeds.
IAC WON'T NAOFFD
The data receiver refuses to negotiate about output formfeed
disposition, or demands a return to the unnegotiated default
mode.
IAC SB NAOFFD DS <8-bit value> IAC SE
The data sender specifies, with the 8-bit value, which party
should handle formfeeds and what their disposition should be.
The code for DS is 1.
IAC SB NAOFFD DR <8-bit value> IAC SE
The data receiver specifies, with the 8-bit value, which
party should handle formfeeds and what their disposition
should be. The code for DR is 0.
3. Default
DON'T NAOFFD/WON'T NAOFFD
In the default absence of negotiations concerning which party, data
sender or data receiver, is handling output formfeeds, neither party
is required to handle formfeeds and neither party is prohibited from
handling them; but it is appropriate if at least the data receiver
handles formfeed considerations, albeit primitively.
4. Motivation for the Option
Please refer to section 4 of the NAOL and of the NAOFFD Telnet option
descriptions.
5. Description of the Option
The data sender and the data receiver use the 8-bit value along with the
DS and DR SB commands as follows:
8-bit value Meaning
0 Command sender suggests that he alone will handle
formfeeds, for the connection.
1 to 250 Command sender suggests that the other party alone
should handle formfeeds, but suggests that the
indicated value be used. The value is the number
of character-times to wait or number of NULs to
insert in the data stream before sending the next
data character.
251 Command sender suggests that the other party alone
handle formfeeds, but suggests that each
occurrence of the character be replaced by
carriage-return/line-feed.
252 Command sender suggests that the other party alone
handle formfeeds, but suggests that they be
discarded.
253 Command sender suggests that the other party alone
should handle formfeeds, but suggests that
formfeeds be simulated.
254 Command sender suggests that the other party alone
should handle output formfeeds but suggests
waiting for a character to be transmitted (on the
other simplex connection) before sending more
data. Note that, due to the assynchrony of the two
simplex connections, phase problems can occur with
this option.
255 Command sender suggests that the other party alone
should handle output formfeeds and suggests
nothing about how it should be done.
The guiding rules are that:
1) if neither data receiver nor data sender wants to handle output
formfeeds, the data receiver must do it, and
2) if both data receiver and data sender want to handle output
formfeeds, the data sender gets to do it.
The reasoning for the former rule is that if neither wants to do
it, then the default in the NAOFFD option dominates. If both want
to do it, the sender, who is presumed to have special knowledge
about the data, should be allowed to do it, taking into account any
suggestions the receiver may make. Simulation is defined as the
replacement of the formfeed character by enough line-feeds (only)
to advance the paper (or line-pointer) to the top of the next page
(or to the top of the terminal screen). Note that delays,
controlled by the data sender, must consist of NUL characters
inserted immediately after the formfeed character. This is
necessary due to the assynchrony of network transmission. As with
all option negotiations, neither party should suggest a state
already in effect except to refuse to negotiate; changes should be
acknowledged; and once refused, an option should not be resuggested
until "something changes" (e.g., another process starts). At any
time, either party can disable further negotiation by giving the
appropriate WON'T NAOFFD or DON'T NAOFFD command.